The present invention relates to the field of automatic devices for guiding articles to be arranged according to desired or preferable patterns in order to locate them, if necessary with a layered configuration, on platforms or pallets for handling forks or other conveying systems.
As is known the industries making goods in large amounts have storing requirements demanding a precise and ordered arrangement of said goods according to patterns which are deemed to be preferential. This is particularly true as said goods are to be arranged in a layered configuration on pallets provided for handling said goods or articles to store or shipping them.
To that end, the above mentioned industries presently use the so-called palletizing machines which are specifically designed for loading pallets. These machines essentially comprise conveyor belts which, according to the most suitable paths, deliver the article (bag, package) to a switching platform whereat it is oriented and sent to any desired place in order to rationally arrange it on the pallet, or over other like articles of an underlying layer which have already been arranged on the pallet.
The articles to be arranged have frequently a parallelepipedal shape and, accordingly, they are to be generally mutually oriented in order to achieve the following results: to occupy a very reduced space; to provide a very strong layered structure; to mutually arrange the articles in such a way as to reduce as much as possible the specific pressure exerted on their surface by the weight on the overlying layers.
FIG. 1 illustrates the surface of a pallet having a square perimeter Z and covered by four rectangular elements a,b,c,d (which may consist of cement bags) arranged according to a perimetrical pattern. FIG. 2 illustrates a subsequent layer formed by other four rectangular elements e, f, g, h (like the preceding elements) which are arranged over the elements a, b, c, d. The different arrangement of the articles of FIGS. 1 and 2 shows that the friction exerted by the weight of the overlying articles allows for the latter to act as a "junction" for the underlying articles, thereby providing the assembly with great stability properties.
FIG. 3 illustrates the surface of a pallet having a rectangular perimeter U, and covered by five rectangular elements i, l, m, n, o which are arranged in an adjoining relationship.
FIG. 4 illustrates a subsequent layer formed by other five articles or elements (like the preceding ones) p, q, r, s, t which are accordingly arranged so as to provide a mirror arrangement of the above disclosed arrangement, to meet the requirements of a maximum use of the pallet surface and maximum strength of the layered assembly.
It should be pointed out that FIGS. 1, 2, 3 and 4 merely show examples of conventional arrangements to clearly stress the requirement of arranging the articles to be palletized at very precise locations. This precision requirement will be more and more stringent as the articles to be palletized are held in delicate or lacerable envelopes and as their weight is comparatively great; an example of these articles is that of cement bags which, as is known, are usually made of paper. In FIGS. 1, 2, 3, 4 there are identified the positions assumed by the elements, having their geometrical center of gravity marked by a dot x. Thus the trajectories y to be followed by the centers of gravity of these articles during their rectilinear longitudinal motion, toward the stop and aligning abutment W, and imparted thereto by specific driving means will be clearly apparent.
Considering that the articles to be arranged arrive at the switching platform from a single trajectory that is determined by a feeding conveyor belt, the problem to be solved is to cyclically transversely offset the mutually different parallel trajectories y to arrange the several articles in the positions shown in the figures according to cyclic sequences of the type abcd, efgh, abcd, efgh (FIGS. 1 and 2); or of the type ilmno, pqrst, ilmno, pqrst, ilmno, etc.
Another way for solving the above problem is to cause the articles to slide on a roller assembly having, between the rollers, raisable and transversely movable rods to raise the article (to move it away from the driving rollers), transversely displace it so as to arrange it on the desired longitudinal trajectory (y), and arrange it again on the roller assembly to reach a stop barrier with the desired orientation and trajectory, in order to obtain the preset layered configuration.
As is known the layered structure or configuration may be formed in several ways. One of them is to pick up the complete layer by means of carriages having suction cups and arrange it on the preceding layer; another of them is to form the layer on shelves which are downwardly displaced to deposit the layer and then upwardly displaced to remove them from the layer (which is suitably held by the vertical wall touched during the downward displacement); another way is to cause the article layer or another preformed layer to fall on the pallet by opening a trapdoor made by transversely displacing two half panels (thereon it was caused to rest), by holding the layer by means of suitable side abutments.
An arranging method is also known consisting of transversely displacing a pallet; however this method has the drawback that the pallet return stroke cannot be used.
In connection with the known method of raising the articles by means of rods arranged between the driving rollers and transversely sliding, it has the drawback that it is necessary to interrupt the feeding of the article.